NASA officials are closely monitoring the debris fields for any hazard posed to the international space station. They’re also concerned about 20 NASA satellites that are in orbits similar to that of the Cosmos and the 66 Iridium spacecraft (which all cross at the poles).

Asked if other satellites might be at risk, Johnson said “technically, yes. What we’re doing now is trying to quantify that risk. That’s a work in progress. It’s only been 24 hours. We put first things first, which is station and preparing for the next shuttle mission.” A shuttle mission, scheduled for Feb. 22, could be delayed.

Most, if not all, of the debris is expected to eventually burn up in Earth’s atmosphere.

In a top secret operation, the U.S. Defense Dept. is conducting the first deep space inspection of a crippled U.S. military spacecraft. To do this, it is using sensors on two covert inspection satellites that have been prowling geosynchronous orbit for nearly three years.

The failed satellite being examined is the $400 million U.S. Air Force/Northrop Grumman Defense Support Program DSP 23 missile warning satellite. It died in 2008 after being launched successfully from Cape Canaveral in November 2007 on the first operational Delta 4-Heavy booster.

The failure of Northrop Grumman’s missile-tracking satellite has sparked concerns that Washington’s longstanding refusal to disclose the location of classified spacecraft, even if they are dead, could boost the risk of disastrous collisions in space. The satellite is still loaded with lots of fuel but no longer responds to commands. “There’s no practical way at the moment to adjust the orbits of dead objects,” said the official.